3 gain stages to 4 gain stages

[MadAsAHatter]

Some of the things he talks about can go over my head, but I always enjoy watching @burger DIY videos. They've helped me understand a lot more about what's going on inside an amp. This one was interesting and pretty straight forward on how you'd make a 3 gain stage 2203/04 into 4 gain stages.

 

[glpg80]

He only covers the exciting easy stuff that will get him views since it’s his full time job. I’m here to crush dreams and say 4+ stages also depends on grounding scheme, layout, wiring, soldering skills, stray capacitances, power calculations so you don’t build a fire hazard, and many other factors like trimming excess frequencies that just waste power. It’s way, way more involved to tune a good sounding high gain amp and even more complicated to troubleshoot a design that has a problem you don’t quite understand. Many times people don’t have the necessary tools they need to properly troubleshoot some of the problems that can come up. High gain means super complicated and the real world isn’t forgiving.

 

[duesentrieb]

Nice vid.
I like Jason, knowledgable guy - and even more butchered 2203s for me

 

[yeoldefortran]

He only covers the exciting easy stuff that will get him views since it’s his full time job.

Well yeah, this is a schematic level overview, it's clearly targeted at folks just trying to wrap their heads around this stuff. And regardless of whether you are going to actually build, I think it's really useful for folks to understand what's actually happening in their gear so they can better identify what they will like.

I do think his older videos are some of the best available and cover a great mixture of practical (how to use an oscilloscope, how to start up a suspect amp) and theoretical (e.g. the role of a cathode resistor). Not gonna turn you into an amp builder on it's own but I'm sure there's a lot of jake mods and NFB pots thanks to him.

 

[glpg80]

Nice vid.
I like Jason, knowledgable guy - and even more butchered 2203s for me

He’s very knowledgeable and happy to help others - no jabbing at him or his super successful model. Anyone that’s designed for high gain knows there’s a lot more that goes into it.

There’s a significant jump from copying something he’s designed and laid out in a walkthrough and Wild West designing and building your own from scratch with no layout to follow.

 

[yeoldefortran]

And please, whatever you do, don't butcher your super clean vintage marshall as your first project

 

[SpiderWars]

I just recently was revisiting my 2204 with this exact thing and my extra stage is very similar to what he is doing here.

I doubled up the triodes on the extra tube and used 100k plate and 1k5//.68u cathode so that should be close. I used a 120pF snubber across the plate-cathode (similar to Marshall).
2n2 coupler, same as Jason.
I used 1M/68k for the voltage divider and I have a snubber in parallel with the 68k, I think it's 560pF.
I made an extra power supply node for the extra stage, 30uF/450v cap.

However my amp is 'stock 2204' when you plug into the Low input, I didn't remove the treble peak circuit before the Gain pot.

In my amp the result is that it sounds like a 2204 but with the best boost ever in front. So it's not really high, high gain. Just boosted 2204 high gain, straight in. It sounds really great.

Here's an older pic before the most recent rework. This is the amp I bought from late forum brother splatter just a couple months before COVID took him. It had already been modded to hell with 4th preamp tube, then modded back to stock by splatter, then modded back to hell by me. It doesn't have any hum/buzz but has some hiss. Resonance control with push/pull NFB switch on back.

 

[glpg80]

I just recently was revisiting my 2204 with this exact thing and my extra stage is very similar to what he is doing here.

I doubled up the triodes on the extra tube and used 100k plate and 1k5//.68u cathode so that should be close. I used a 120pF snubber across the plate-cathode (similar to Marshall).
2n2 coupler, same as Jason.
I used 1M/68k for the voltage divider and I have a snubber in parallel with the 68k, I think it's 560pF.
I made an extra power supply node for the extra stage, 30uF/450v cap.

However my amp is 'stock 2204' when you plug into the Low input, I didn't remove the treble peak circuit before the Gain pot.

In my amp the result is that it sounds like a 2204 but with the best boost ever in front. So it's not really high, high gain. Just boosted 2204 high gain, straight in. It sounds really great.

Here's an older pic before the most recent rework. This is the amp I bought from late forum brother splatter just a couple months before COVID took him. It had already been modded to hell with 4th preamp tube, then modded back to stock by splatter, then modded back to hell by me. It doesn't have any hum/buzz but has some hiss. Resonance control with push/pull NFB switch on back.

Hiss is expected in high gain design. There’s nothing really you can do to remove it as it’s due to resistor noise. However hum, whistling, or warbling in the noise is due to instability and those have to be resolved.

 

[glpg80]

And please, whatever you do, don't butcher your super clean vintage marshall as your first project

You know a long time ago I used to say the same thing. But given how Marshall can’t keep up with their own reissue demand even today, I say you only live once and if you want to dabble in finding your own sound in your vintage Marshall go for it. The problem with older Marshall’s is that they typically need TLC to find leaky capacitors in both senses and general maintenance before modding which people don’t typically do. I found all kinds of messed up pots in my own donor amp. It goes back to what I said earlier about troubleshooting - you can’t build mods on an already unhealthy amplifier.